e-mosty March 2019 Long Span and Multiple Span Bridges - Page 22

The Puente Chacao project has been in development for the past two decades. Initial studies by the Chile Ministero de Obras Publicas (MOP) began in the late 1990s resulting in a 1997 investment study and a technical feasibility study in 2001. Preliminary geotechnical investigations began in 2000. The Public Private Partnership (PPP) procurement was terminated in June 2006, when the consortium indicated that the bridge cost would be greater than the financial limit imposed by the Government of Chile. The project restarted in 2012 when a Design Build (DB) contract was adopted. The deck profile provides for a 600 meter-wide by 50-meter high main navigation envelope under the north main span. The Contract was awarded to the Consorcio Puente Chacao (CPC) in February of 2014. The international DB consortia members include Brazilian company OAS, South Korean Hyundai, French Systra and Norwegian Aas-Jakobsen. One distinctive feature of the Puente Chacao is the use of continuous cables over three pylons to support two main spans, which results from unique site features. Pylon top elevations are between +157.2 and +198.6 meters. With the exception for the anchorages, all major bridge elements are supported on deep pile foundations. Other project elements include four lane roadways to connect the bridge to existing Route 5 sections at both project limits; and buildings that accommodate bridge services and a public interpretive center. The 2.5-kilometer-wide Chacao Channel has water depths of up to 125 meters at the crossing location. However, one notable exception is a rock mass extending upward from the seafloor to nearly sea level at Roca Remolinos (Whirlpool Rock) at the middle of the channel. The owner's engineering team is a joint venture of COWI and Chilean firm RyQ. Final design began early in 2014, and construction of portions of the bridge pylon foundations began in early 2018. The completed final design was accepted by MOP in late 2018. PROJECT ELEMENTS ARRANGEMENT AND GENERAL Results of a preliminary exploration program indicated that the geology of Roca Remolinos could feasibly support construction of a major bridge foundation. BRIDGE Major project elements include a 2,754-meter long suspension bridge consisting of two suspended main spans of 1055 and 1155 meters; a 324-meter long suspended North Side Span; a 140-meter- long three span South Approach Viaduct; three reinforced concrete pylons, and two main cable anchorages. Preliminary studies also identified that a continuous, multi-span suspension bridge would be more economical than a more conventional suspension bridge design with two pylons and a single main span. Similar studies of single and two span cable stayed bridge alternatives reached the same conclusion. Figure 1: Roca Remolinos 1/2019